Modifies the Classes attribute of the specified OSI Transport
    Template instance to include at least the specified class or
    classes.

    add  [node node-id] osi transport template template-id -
          classes {class[,class...]}

    The Classes attribute is a set of protocol classes that can be
    negotiated for use on a transport connection.  If the value of
    the Network Service attribute is CLNS, the class must be a subset
    of the classes supported by the OSI Transport attribute CLNS
    Classes Supported.  If the value is CONS, the classes must be
    a subset of the classes supported by the OSI Transport attribute
    CONS Classes Supported.  If the value of the Network Service
    attribute is ANY, the classes must be a subset of the combined
    classes in the CLNS Classes Supported and CONS Classes
    supported attributes.

    Example:

    add node remnod osi transport -
          template osit$loop_cons classes {0,2,4}